1. Field of the Invention
This invention relates to a disc drive, and more particularly relates to a disc drive for reproducing or reproducing and recording a disc-shaped recording medium such as an optical disc.
2. Description of the Prior Art
Disc drives are apparatuses for at least reproducing information recorded in a disc-shaped recording medium such as a compact disc and CD-ROM and the like. In these recording mediums, information is recorded on a signal recording surface (information recording surface) of the disc through a number of pits spirally formed on the information recording surface. By emitting a laser beam onto the surface, the information is reproduced through changes in the magnitude of the light of the reflected beam. Examples of such a disc drive include CD players, CD-ROM drives, DVD drives and the like.
One example of such disc drives is disclosed in Japanese Laid-open Patent Application No. 10-293932 which was filed by the assignee of this application. FIG. 27 is a perspective view of the conventional disc drive and FIG. 28 is an exploded perspective view thereof.
As shown in these drawings, the disc drive 1B comprises a casing 10 having a bottom cover and an outer cover 10b, a main printed circuit board 11 of which width and length are substantially the same as those of the bottom cover 10a of the casing 10, and a chassis provided above the printed circuit board 11. The chassis 40 is formed into a roughly rectangular container-shape having substantially the same width and length as those of the bottom cover 10a. These components are housed within the casing 10 constructed from the bottom cover 10b and the outer cover 10a. The chassis 40 has a bottom portion 40a in which a rectangular shaped opening 41 is formed. In the opening 41, a mechanism unit 42 on which a turntable 46 for rotating a disc 3, a spindle motor for rotating the turntable 46, and an optical pick-up 30 for reproducing or reproducing and recording the disc 3 and the like are provided.
Further, a disc tray 5 for transporting the disc 3 from the outside of the casing into the casing 10 is provided on the chassis so as to be slidably movable with respect to the chassis 40 in the forward and rearward directions.
As described above, the main printed circuit board 11 used in the disc drive 1B has substantially the same width and length as those of the bottom cover 10a of the casing 10, so that the entire surface of the bottom cover 11a of the casing 10 is covered by the printed circuit board 11. When such a printed circuit board 11 is used, it is necessary to form openings 11a and 11b in the printed circuit board 11 as shown in FIG. 28 for connecting the optical pick-up 30 to a connector 45e provided on the under surface of the printed circuit board 11 using a flat cable 30a and for connecting the spindle motor 45 to a connector 45d using a flat cable 45c. This results in the complicated shape of the printed circuit board 11.
Further, as described above, since the printed circuit board 11 used in the conventional disc drive 1b has substantially the same shape as that of the bottom cover 10a of the casing 10, that is a large size printed circuit board is used, many screws are necessary to mount the printed circuit board to the chassis 40, which results in increased assembling steps.
Furthermore, in the conventional disc drive 1B, in order to mount the printed circuit board 11 to the chassis 40, it is necessary to reverse the chassis 40 two or more times when assembling the disc drive, which also results in complicated assembling process.
In order to solve the problems in the conventional disc drive, the present invention is directed to a disc drive, comprising: a disc tray on which an optical disc is to be placed, the disc tray being movable between a disc ejecting position and a disc reproducing position in front and rear direction; a loading chassis which supports and guides the disc tray during the movement thereof; a feed chassis on which a turntable for rotating the disc and an pick-up at least for reproducing the optical disc are provided, said feed chassis having a rotation axis and a forward portion which is a front side of the rotation axis and on which the turntable and pick-up are arranged, and the front forward portion of the feed chassis being displaceable between a raised position and a lowered position about the rotation axis; a main circuit board having various electrical elements for controlling the turntable and the pick-up arranged on the feed chassis; a casing composed of a bottom cover and an outer cover for housing these elements, the bottom cover having left and right sides; and a pair of feed chassis supporting members respectively provided at the left and right sides of the bottom cover, in which the feed chassis is pivotally supported by the feed chassis supporting members and at least a part of the main circuit is supported by the feed chassis supporting member.
According to the disc drive having the above structure, it is possible to provided a disc dive in which a main circuit board can be easily mounted, thus leading to easy assembling operation.
In the present invention, it is preferred that the bottom cover has a roughly front-half part and a roughly rear-half part, and the loading chassis is arranged on the front-half part and the main circuit board is arranged on the rear-half part, respectively, in such a manner that they are separated from each other. According to this structure, both the loading chassis and the main circuit board cam be directly mounted to the bottom cover of the casing, and this leading to easier assembling operation.
Further, in the present invention, it is preferred that one of the feed chassis supporting members is formed with a positioning means for positioning the main circuit board. In this case, it is also preferred that the positioning means includes a rib which is formed with the feed chassis supporting member and a notch formed in the main circuit boar so as to be engageable with the rib. This also makes it easier to assemble the components of the disc drive.
Furthermore, it is also preferred that one of the feed chassis supporting members is formed with a recess to which the main circuit board is fitted. This also makes it easier to assemble the components of the disc drive.
Moreover, it is also preferred that bottom cover has a pair of upwardly protruding circuit board mounting portions which are located along one of the orthogonal lines of the main circuit board, and the main circuit board is mounted onto the circuit board mounting portions via screws. In this case, it is preferred that one of the circuit board mounting portions is used for grounding the main circuit board.
Moreover, it is also preferred that the electrical parts on the main circuit board includes heat generating electrical parts which are mounted on the under surface of the main circuit board, and heat dissipation sheets are provided between the electrical parts and the bottom cover for transmitting heat generated in the electrical parts to the casing.
Another aspect of the present invention is directed to a disc drive, comprising: a casing having a bottom cover and an outer cover which is joined to the bottom to form a substantially box-shape, the bottom cover having a roughly front-half part and a roughly rear-half part; a disc tray on which an optical disc is to be placed, the disc tray being movable with respect to the casing between a disc ejecting position and a disc reproducing position in front and rear directions; a loading chassis provided within the casing for supporting and guiding the disc tray, the loading chassis being designed so that it is arranged on the front-half part of the bottom cover of the casing; a feed chassis which is provided within the casing and on which a turntable for rotating the disc and an pick-up at least for reproducing the disc are provided, the feed chassis being pivotally displaceable between a raised position at which the disc can be reproduced and a lowered position at which the disc tray can be moved between the disc reproducing position toward and the disc eject position; and a main circuit board having a roughly rectangular shape and having various electrical elements for driving and controlling the disc drive, the main circuit board, being provided within the casing and designed so that it is arranged on the rear-half part of the bottom cover.
According to the structure described above, it is possible to provide a disc drive in which the main circuit board can be mounted easily, since the feed chassis and the main circuit board are separately mounted to the bottom cover directly.
In this structure, it is preferred that the disc drive disc drive further comprises a pair of feed chassis supporting members which are respectively provided at the left and right sides of the bottom cover, in which the feed chassis is pivotally supported by the feed chassis supporting members. In this case, it is preferred the feed chassis is supported by the feed chassis supporting members through elastic members, and the feed chassis is pivotal with respect to an axis connecting the elastic members due to elastic deformation of the elastic members. In this case, it is further preferred that the feed chassis includes a base plate formed into a roughly cross shape having a front extending part, a right extending part, a left extending part and a rear extending part, and the elastic members are provided on the right extending part and the left extending part of the base plate, respectively. These arrangements make it possible to effectively prevent vibration caused by the rotation of the disc from being transmitted to the casing.
Further, in this invention, it is preferred that the feed chassis includes a base plate formed into a roughly cross shape having a front extending part, a right extending part, a left extending part and a rear extending part, and the base plate is designed so that its width including the right extending part and the left extending part is substantially equal to the width of the bottom cover. Use of such a base plate makes it possible to increase the weight of the feed chassis, and this is effective in suppressing the vibration. In this case, it is preferred that each of the right and left extending parts of the base plate has a rear corner, and the feed chassis is pivotal with respect to a pivotal axis connecting points near the rear corners of the right and left extending parts of the base plate.
Furthermore, in this invention, it is also preferred that the disc drive further comprises a mechanism for displacing the front extending part of the base plate in up and down directions. Preferably, the displacing mechanism includes a cam mechanism having a cam which converts rotational motion of the cam into the up and down motion of the front extending part of the base plate.
Moreover, in this invention, it is also preferred that the disc drive further comprises means for supporting and positioning the rear end portion of the disc tray with respect to the rear plate of the casing. Preferably, the supporting and positioning means includes engaging means elastically provided in the rear end portion of the disc tray and engaged means formed on the rear plate of the casing, wherein the engaging means comes to abutment with the engaged means with the engaging means being elastically deformed when the disc tray reaches the disc reproducing position. In this case, it is more preferable that the engaging means includes a pair of elastic arms which are inwardly provided at the opposite rear corners of the disc tray such that they face each other, and each elastic arm includes a leaf spring shaped elastic part which is flexible only in the front and rear directions and an engaging part formed on the tip part of the elastic part. Further, it is also preferred that the engaging part of each elastic arm is formed with a plurality of horizontal grooves and the engaged part of the rear plate of the casing is also formed with a plurality of corresponding horizontal grooves.
These arrangement makes it possible to support and position the rear end part of the disc tray with respect to the rear plate of the casing, and this is very effective in the disc drive of the present invention in which the loading chassis for supporting and guiding the disc tray is designed so that it is arranged on the front-half part of the bottom cover of the casing.
Moreover, in this invention, it is also preferred that the disc drive further comprises means for preventing a disc which has been removed from the disc tray within the casing from being left inside the casing when the disc tray is ejected. Preferably, the means includes a projection extending from the top plate toward the disc tray, and the projection is provided on the top plate so that the projection is positioned near and outside the outer periphery of the disc placing portion of the disc tray when the disc tray is in the reproducing position.
These and other objects, structures and advantages of the present invention will be apparent when the following detailed description of the preferred embodiments will be considered taken in conjunction with the appended drawings.